The present invention concerns a power source apparatus for an electric powered automobile.
One type of electric automobile, the hybrid car, operates by driving the wheels via an engine, and an electric motor. As a power source to run the motor of such an automobile, a driving battery configured with battery modules of many series-connected rechargeable batt eries (nickel cadmium batteries, nickel hydrogen batteries, lithium ion rechargeable batteries, etc.) is carried on board. This driving battery is charged using a generator powered either by the engine or by regenerative braking which utilizes the automobiles inertia during stopping.
Long lifetime, high reliability, and safe operation are required of the driving battery. Consequently, charge capacity and discharge capacity are normally regulated to prevent over-charging or over-discharging of each rechargeable battery of the driving battery and to keep remaining capacity of the driving battery within a set range (for example, 40% to 60% of full charge).
For this type of driving battery, charging and discharging must be controlled to maintain driving battery remaining capacity within the set range. Consequently, driving battery remaining capacity must be accurately computed.
Further, the driving battery is configured with many rechargeable batteries connected in series. Therefore, if battery capacity differentials develop between individual rechargeable batteries, there is risk of detrimental effects from over-charging or over-discharging a battery or batteries in one section.
In general, a driving battery comprising rechargeable batteries will have memory effect and self-discharge, as well as output decrease in low temperature conditions.
The present invention was developed to effectively resolve these shortcomings. It is thus the first object of the present invention to accurately compute driving battery remaining capacity.
The second object of the present invention is to effectively eliminate driving battery component battery capacity differentials.
Further objects of the present invention are to suppress driving battery memory effect and self discharge in an optimum fashion, and to prevent output decrease in cold temperature conditions.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.